Continuous annealing and cleaning process



July 16, 1929. H. M. NAUGLE ET AL CONTINUOUS ANNEALING AND CLEANING PROCESS Filed Nov. 17. 1924 2 Sheets--Sheai July 16', 1929. H. M.-NAUGLE ETAL CONTINUOUS ANNEALING AND CLEANING PROCESS Filed Nov. 1'7, 1924 2 Sheets-Sheet 2 17 /il /Vauyla and Jw/se/zd 35% auf nd/ul www Patenten July 1e, 192e.,

unirel sra-ras l amsn HARRY NAUGLE AND ARTHUR J.TOWNSEND, F CANTON, OHIO, ASSIGNORS; BY-v MESNE ASSIGNMENTS', fro 'rain AMERICAN nonnina MILL company; @MIDDLE Town', omo, a conroaerron or. omo. 1

conrrnncnsnimnemneann creanmeraccnss;

eppneaamaiee .novemberintese..v .eener ab. recare-.

The invention, vrelates tov .a'i continuous method for quickly Y amlealingv .a strip of sheet metaL-referred to in ,a generalway 1nl our application :for method of makirlgstrip sheets lfiled `August 22,11922, Serial Y Yumher 583,612; matured in Patent- Na 11,536,028,

.dated April 28, 1925,;a'ndreissued .J une 14, 1927, Reissue No. 15,652; andthe 'general ole-- ject .of they improvemenaisfto anneal ,the metal in a manner that will give the product the uniform Aductile and other structural characteristics which are necessary for deep drawing and vforming or stamping opera: tions.

A readjustment of the grains of the metal to relieve them of the strains produced by aA rolling operation, and more particularly by a rapid cold rolling reduction, cannot be accomplished by the ordinarybox annealing 'of a mass or coil of metal, fo'rthe reason that the longer period of time required for properly heating the inner portions of the mass or coil, not only results in the overannealing of the outer portion thereof, butin the production of a grain growth in a considerablel portion of the mass or coil, which destroys the ductility and uniformity, and also decreases the strength of the material in the outer portions of the mass or coil.

The present improvement is particularly concerned with the annealing of steel having a carbon content of less than .20%, for the reason that such va low carbon steel is best suited for deep drawing and forming orV stamping operations; and for properly zinnealing the same, the metal must be uni formly heated to a temperature of from 1300 to 1600 F. As a grain growth, sometimes known as Steads brittleness, mayv occur at a: temperatureless thanA 1400 F. if the same is maintained long enough; one object of the present improvement is to ,uni-

formly heat the 'metal lto an annealing tem- The general vobject of the improvementv meylpefeealieeal ty: taining-. at'. eine eey-f the direct action o'f 'electric resistors, while?.

n chamber, inswhichz- :the resistors are trans-4v Vel'Sly. locatedA adjacent to and-parallel with the strlp, by whlchthe same may bel uni-formly heated and ,the degreefo. heat vdenitely controlled atall points Ain. the heatingur '.f nace; and then .to promptlycoolvthe .stripsy by moving 1t continously through.a'fabular1 ductlsurrounded by .a movingbodyo water or other heat absorbing liquid, by whichv the.

strip may-be. quickly and gradually reduced to .a nonpxidizing temperature v when 'eX-b posed to the air.

The particular objectofthe present :improvement isto avoid or overcome diculties wh1ch may accompany the continuous annealing processes set forth in our applicationfor-patent, tiled April 4, 1924, Serial No. 704,157, and the use of the continuous annealing apparatus set forth in our application forY patent filed herewith, Serial Num- 'ber 750,269; in both of which an edort is! made to carry on the heatingand cooling operations inv thepresence of a neutral ora reducmg gas to the exclusion of air, -for preventing or removing an oxidation or discoloration. of the surface of the strip.

. The very desirable and highly eflicient use of electric reslstors for directly heating a strip of steel or the like for annealing the same'in a chamber containing a reducing gas, requires the use of a refractory lining for the annealing chamber and preferably requires lso the use of a liquid seal for the opening through which the strip enters the chamber. It has been found, however, that the use 'of a deoxidizing medium in theheating chamber has an injurious ei'ect uponthe electric resistors, and the vapors resulting from the Y volatilization of a liquid sealing medium has a deteriorating effect upon the refractory lining.

The present improvement avoids these dif' ficulties by the use of an unsealed heating chamber, vin whichy some atmospheric .gas may slightly oxidize or discolor the surface ofthe strip; and by interposing between the heating chamber and the coolingduct of the annealing apparatus, a heat. retaining deoxidizing duct containing a reducing gas for removing any oxidation or discoloration there may be on the strip when it leaves the heating chamber, while in the heated condition. h

By these means, the detrimental effect upon the refractory lining of the` heating chamber b the va ors resultin from 'volatilization therein o a liquid sealm medium, and the damaging action of a re ucin gas upon the electric resistors within the eating chamber, are both avoided; and the heated strip is com letely cleaned of any discoloration or oxidation which ma be present on its surface, before it enters t e cooling duct.

The improved method may be carried out by the apparatus illustrated, more or less continuous in the accom anying drawings forming part hereof, in w ich- Figure 1 is a side elevation, partly in section, of the improved apparatus, showing an asbestos seal between the heating and oxidizing ducts;

Fig; 2, an enlarged longitudinal section of an asbestos seal;

Fig. 3, is a. cross section through the deoxidizing duct as on line 3 3, Fig. 1; and

Fig. 4, a fragmentary side elevatlon, partly in section showing a liquid seal between the heating and deoxidizing ducts.

Similar numerals refer to similar parts throughout the drawings. The apparatus may include a coil box A, a strip leveler B, a traveling spot Welder C, a solution washer D, an electric heating furnace E, an asbestos seal F, a deoxidiz- Iing duct G, a cooling duct H, an exit seal I, conveyer rolls J a double end shear K, and a strip coiler all arranged in series as shown in Fig. 1.

The coil box A may be of any ordinary construction for holding a coil 10 of a strip 11 of steel or the like, and permittin the same to unwind for a continuous annea ing; and the strip leveler B may include two sets of rolls 12 o f an we ll known construction and operation, or flattening the sheet and removing uneven fullness or .buckles which ma have been caused by reducing rolls or ot er apparatus used in producing the strip.'

The spot Welder C may include a set of electrodesv 13 mounted in a frame 14 supported on a carriage 14 provided with wheels 15 riding on a track 16, together with gripping'devis' 14.- on the front and rear sides of the frame, for clamping and holding successive strips with .their ends overlapped, inv position between the electrodes for a spot welding operation while the -care is traveling forward on the track.

vhe solution washer D may include strip supporting rolls' 17 and transverse tubes 18 suitably apertured for, spraying ahot soda solution upon the strip, to remove grease vward by springs 30 and and rit therefrom, and like tubes 18 also provided for air rear of the cleaner. U The heating -furnace E may include a cylm'dric shell 20 mounted on supports 21 lined with a thick body of heat insulating material 22, within which is provided a lining of fire brick 23 or other refractory material formlng a support for electricresistors 2A and 24 parallelly ositioned above and below and forming tween them a longitudinal heating chamber 25, in which are provided a series of transverse skids 26 for sup'- porting a strip 11 as it is moved endwise through the furnace from the entering lslot 20 at its front end to the asbestos seal F at its rear end.

`By these means, the strip may be heated directly by the action of the' electric' resistors, ina uniform manner from end to end of the furnace, and the degree and continuity of heat can'fbe readily controlled at al1 points in the heating chamber, by referring to the series of' yr "eters 25':

The asbestos seal IP ma include a box 27 with slots 27 in each end or freely passing a strip sheet 11; above and below which the may drying the strip in box is filled with fibrous asbestos 28, supported below by abottom plate 29 pressed upcompressed from above by weight lates 31, so as to form a seal by pressin t e asbestos against a strip as it is drawn t rough a box.

The sealing box 27 -may be connected to the rear end of the annealing furnaceby a flanged funnel nipple 32 andto the front end ofthe oxidizin duct by a flanged tubular nipple 31'; w ich nipples are preferably surrounded by an asbestos packing 32 and 32 for retaining the heat.

A water seal F? as shownin Fig. 4 may be used in place of the asbestos seal F and when used, the strip 11 may be guided through the water seal by means of guide rolls f and f' in well known manner.

The deoxidizingduct G may be formed by a metal.' chamber 33 and a cover 33 mounted on transverse I-bars 34 in a trough channel 35, within which the duct is entirely surrounded with. an asbestos packing 36 for retaining the heat within the duct; the chamber being rovided with anv inletI pipe 33 and an ou et pipe 3 3" for passing a,

metaalL 3 water from the forward toward the reary end of each trough. y i

The exit seal I may be of the liquid type provided with guide rolls 36 and 36; and maybe provided with an inlet' pipe for sup-v plying the same with sealing water or otherv shearing punch 40 operating between them,

for shearing the joint of two strips in front and 1n rear of their overlapped ends, so as to neatly disconnect them after the anneal- .ling process is completed. i f l The strip coiler L may be of an well 'known construction for' winding t e annealed strip 11 into'a coil-10.'and it is 4preferably provided with 'an` independent motor 34 for this purpose.` i j i In the operation of the'apparatus, astrip sheet, which has been flattened by thelev'eler B, joined to another strip by spotwelder C,

and acted upon by the solutionwash'e'r D is movedv continuously endwise through the heating chamber 25, the deoxidi'zingduct and the cooling duct H; wherein` it isiheated rapidly and uniformly by the' electric resistors to an annealing temperature, which temperature is maintained and continued only for the brief period necessary for a proper v, annealing of the metal, which' may not ex.- i

ceed one minute, whereuporgit isdeoxidized in the duct G and then promptly cooled gradually by the heat absorbing waterl surrounding the tubular duct:

In this manner a continuous quick annealing and cleamnglis accom lished, and

the comparatively brief period uring whichvv the annealing temperature ismaintamed and continued, prevents the production ofan objectionable grain growth or 5 Steads brittle-v ness, so that the annealed stripthus pro-' duced is Vcharacterized `by a uniformly line l grainedstructure anda highly ductile quality, which-adapt it for deep drawing operations.

By the improved apparatusstrip sheets` of different gauges and of more` than ordinary widths can be continuously annealed lwithout developing any` objectionable graingrowth.

In actual practice any given `portion of a strip sheet, one-sixteenth of van' inch in vthickness may be heated to v a temperature'. of

'1600 E., maintained at that temperature. for about one minute, and then-cooled to a non.

oxidizing'temperature, all within a period of about three minutes. This operation can be carried on continuously with respect to all portions of each strip, and ofv successiveV strips which have been joined together, without stopping the movement of the strip which is passing through the heating chamber, the .deoxidizing duct, andthe cooling duct.

Reference is made to our applications for..

patent iledNovember 17, 1924, Serial Num'- ber 750,271 and the continuation thereof filed i July `1, 1925,- Serial Number 40,739, containingclaims for subject matter-disclosed butv not claimed therein. l v lVe claimz-` 1. The method of annealing the body and cleaning the surface of a steel strip which includes uniformly heating the stri-p to an-l nealing temperature, then deoxidizing the surface ofthe strip while inthe heated condition, and thencooling the body thereof,

all during ay continuous en'dwise movement 'ofthestrip f f l 2. The method'of annealing the'body and cleaning .the surfaceI .of a steelfstrip which includes uniformly' heating the strip to annealing temperature' iin an atmospheric gas, and then deoxidizing the surface of the strip while-inthe Aheated condition, and subsequentlyf cooling the vbody thereof in a reducf ingv gas, all rduring a continuous `endwise movement oftheV strip.

Intestimony that we` claim theabove, we have Vhereunto'subscribed our names. v

` HARRY M. NAUGLE. j Y# ARTHUR J. T oWNsEND. 

